Structural sheet



Y Jan. 18, 1955 J. A. POTCHEN STRUCTURAL SHEET Fil ed June 8, 1949 2Sheets-Sheet 2 ll HI l INVENTOR. 6630/? United States Patent STRUCTURALSHEET Joseph A. Potchen, 'Grand Rapids, IVIich assignor to HaskeliteManufacturing Corporation, Grand Rapids, Mich., a corporation of NewYork The invention relates to structural sheets or panels.

A desideratum in embossed sheets of the structural type is maximumstiffness or strength against transverse bending stresses onsubstantially any angular line across the sheet and one object of theinvention is to provide an embossed panel or sheet embodying thisdesideratum.

Another object of the invention is to provide an embossed sheet which isadapted to form the core of a hollow panel and provide the maximumtransverse stiffness against bending stresses with lightness in theoverall weight of the hollow panel.

Another object of the invention is to provide an embossed panel with astructural formation which can be produced at a low cost and providesmaximum transverse stiffness against bending stresses.

Other objects of the invention will appear from the detaileddescription.

The invention consists in the several novel features hereinafterdescribed and more particularly defined by the claims at the conclusionhereof.

In the drawings:

Fig. 1 is a plan of a sheet embodying embossed formations in accordancewith the invention;

Fig. 2 is a section taken on line 22 of Fig. 1;

Fig. 3 is a side elevation of a hollow panel including outer sheets, anda sheet of embossed metal in accordance with the invention;

Fig. 4 is a section taken on line 4-4 of Fig. 3;

Fig. 5 is a section taken on line 5-5 of Fig. 3;

Fig. 6 is a section on an enlarged scale of the border construction inthe hollow panel.

The structural sheet embodying the invention as illustrated in Figs. 1and 2 consists of a sheet of suitable metal, such as aluminum or othersuitable material. The sheet is embossed to provide series of areas onboth faces of the sheet which are adapted to be bonded to facing sheetsto form a hollow panel. The form of the embossed areas is designed toprovide maximum structural strength against bending by reason of thecontour of and the inter-relation of the embossed areas. These embossedareas are adapted to stiffen the sheet against bending along any lineextending across the sheet, such as horizontally, vertically,diagonally, or on any other angular line. The structural sheet is formedfrom a flat sheet of metal or other suitable material, portions of whichare left coplanar to provide areas for bonding the structural sheet to afacing or finishing sheet and the outer faces of the embossed portionsare coplanar to provide surfaces to which an opposite facing orfinishing sheet may be bonded. The beveled connecting portions betweenthe opposite face portions during the embossing operation are stretchedto increase their rigidity while the opposite face portions are leftsubstantially unstretched.

The structural sheet is provided substantially throughout its entirearea with embossed areas of like contour. Each embossed area includes aflat face portion 20, four rounded or curved outwardly projectingcorners 22, incurved ends 23 between the corners at each end, andincurved side-portions 24 with central bulges 25. Corners 22, ends 23,side-portions 24 and bulges 25 are angular in cross-section between theface-portions 20 and the opposite face of the sheet as indicated at 27.The rounded corners 22 conform in contour or curvature to the incurvedside-portions 24, and the incurved ends 23 conform in contour to thebulges 25 and the incurved side-portions 24. The ends and sides ofcontiguous embossed areas are spaced apart leaving flat portions 27between them.

The embossed areas are arranged in rows extending crosswise of eachother. Each row includes alternate embossed areas which extend crosswiseof each other. The embossed parallel areas in one row are staggeredrelatively to the parallel embossed areas in adjacent rows. This resultsin providing vertical rows with alternating areas extending crosswise ofeach other and horizontal rows with alternating embossed area'sextending crosswise of one another. Each embossed area is correlated tothe contiguous embossed areas so that its incurved ends 23 and portionsof its rounded corners 22 will conform to the contiguous incurvedside-portions and bulges 25 of contiguous. crosswise arranged embossedportions, and its incurved side-portions 24 and bulges 25 will conformto the incurved ends and rounded corners 22 of contiguous crosswiseembossed areas, as illustrated in Fig. 1. As a result transverse bendingmoments applied to the sheet in any direction will produce stresses onlines which will intersect a plurality of the portions of the embossedareas or of arched or inclined cross-section and curves so as to stiffenthe sheet against all such stresses.

In Figs. 3 and 4 of the drawing the embossed sheet functions as a corefor a hollow panel which comprises facing sheets 35 and 36 having theirmargins folded together to form closed edges for the panel and areinforcing channel bar 37 extending around all of the edges of thepanel and fitting between the overlapped edges of the facing sheets andthe margins of the embossed core. The embossed sheet extends between theedges of the panel and the facing sheet 35 is bonded by a suitable highstrength adhesive to all of the face-portions 20 of the embossed areas.The facing sheet 36 is likewise bonded to the outer face of all of thecoplanar portions 27 of the embossed sheet. This construction whenformed of aluminum provides a lightweight hollow panel which possesses ahigh degree of stiffness against bending. It may be advantageously usedas a substitute for a panel composed of a solid plywood core with metalfacing sheets bonded thereto because the embossed structural core may befabricated at a low cost and has a high degree of transverse stiffness.

The structural sheet of the invention is adapted for any use in whichstiffness against bending is a factor. It also provides a low-cost corefor a hollow structural panel. The structural sheet has great advantageswhen formed of lightweight metal, such as aluminum, but may also beadvantageously used for structural sheets or other suitable material,such as plastic, where structural strength and stiffness against bendingand cost of production are important factors.

The invention is not to be understood as restricted to the details setforth since these may be modified within the scope of the appendedclaims without departing from the spirit and scope of the invention.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

1. A structural sheet provided with embossed areas, each provided with aface portion, ends, incurved sides and outwardly projecting roundcorners joining the sides and ends, said ends, corners and sides beingbeveled in cross-section, the alternate embosed areas extendingcrosswise of each other, the embossed areas being spaced and correlatedso that the sides of each embossed area w ll conform in contour to theends of contiguous crosswise areas and its ends will conform in contourto the sides of contiguous crosswise extending areas, for stiffening thesheet against transverse bending on substantially any line, the portionsof the sheet between the embossed areas being coplanar.

2. A structural sheet provided with embossed areas, each provided with aface portion, incurved ends, incurved sides with central bulges andoutwardly projecting round corners joining the sides and ends, saidends, corners and sides being beveled in cross-section, the alternateembossed areas extending crosswise of each other, the embossed areasbeing spaced and correlated so that the sides of each area will conformin contour to the ends of contiguous crosswise areas and its ends willconform in contour to the sides of contiguous crosswise extending areas,for stiffening the sheet against transverse bending on substantially anyline, the portions of the sheet between the embossed areas beingcoplanar.

3. A structural sheet provided with embossed areas, each provided with aface portion, ends, inset sides and outwardly projecting corners joiningthe sides and ends, said ends, corners and sides being beveled incross-section, the embossed areas being arranged in rows with alternateareas extending crosswise of each other, the sid of each alternateembossed area in one row extelghng in one direction conforming incontour to the en s and portions of the corners of contiguous crosswiseextending areas, the ends and corners of each of said alternate areasconforming in contour to the sides of contiguous crosswise extendingareas, the portions of the sheet between the embossed areas beingcoplanar,

4 the embossed areas being correlated for intersection by bendingstresses and stiffening the sheet against transverse bending onsubstantially any line.

References Cited in the file of this patent UNITED STATES PATENTS973,442 Lees Oct. 18, 1910 2,441,476 Ewald May 11, 1948 2,304,718 SwartDec. 8, 1942 March 24, 1948, issue of Steel, pages 94-97, 119 and 120.

